Generally, an inkjet printhead of a printer is an apparatus that ejects, sends, or discharges fine droplets of a printing ink on a desired area of a recording medium to reproduce a predetermined image, such as a color image on the recording medium. Inkjet printhead can be generally classified into two types according to the mechanism that is used to eject the ink droplets. A first type of inkjet printhead is a thermal inkjet printhead in which the ink droplets are ejected by an expansion force produced by bubbles generated when the ink is heated up by a thermal source. A second taupe of inkjet printhead is a piezoelectric inkjet printhead in which the ink droplets are ejected when pressure is applied to the ink by a deformation of a piezoelectric element.
The mechanism that is used to eject ink droplets from a thermal inkjet printhead will be described below in more detail. A pulse current is applied to a resistive heating material or heating element in a heater such that ink in an ink chamber that is close to or adjacent to the heater is immediately heated up to about 300 degrees Celsius (° C.). When heated, the ink boils and produces bubbles that expand and pressurize the ink within the ink chamber. As a result, the ink in the ink chamber that is located near a nozzle of the inkjet printhead is ejected or discharged through the nozzle as ink droplets.
To improve the printing quality that can be achieved using inkjet printheads, it is desirable that the ejection speed and the mass of the ink droplets ejected from the inkjet printhead be maintained uniform through a wide range of environmental and/or operational conditions of the printer. The nozzles in an inkjet printhead generally have different print logs according to the printing data that is provided to each of the nozzles. As a result, temperature conditions can be different around each of the nozzles in the inkjet printhead. Moreover, when printing for the first time, changes in the printing environment, such as a change in the temperature outside the printer, for example, can affect the characteristics of the ejected ink droplets. Accordingly, by compensating for temperature changes that occur around each of the nozzles, the mass and/or the ejection speed of the ink droplets ejected from the inkjet printhead nozzles can be maintained substantially uniform across the nozzles.